1. CH. 8 and 10 Plate Tectonics and Reshaping Earth’s Surface

2. Vocabulary Crust: outermost solid layer of Earth. The part we live on Mantle: part below the crust, contains most of Earth’s mass. Core: innermost layer of Earth. Lithosphere: Earth’s crust and upper mantle make up this part

3. Vocabulary Continental Drift: theory the continents drifted apart in the past and continue to do so Plate Tectonics: theory that explains how the lithosphere is broken into moving plates that float on a layer of partly melted rock Plate Boundary: area where 2 plates meet Fault: at a fracture boundary where plates slide past each other. It is a break in the Earth’s crust

4. Vocabulary Sediment: solid particles moved from one place to another Weathering: process of breaking down rock into smaller pieces Mechanical Weathering: weathering when water and ice break down rock. Minerals that make up rock do not change Chemical Weathering: weathering where the minerals that make up the rock change.

5. Vocabulary Erosion: process by which soil and sediments are transferred from one location to another Deposition: adding sediments to a new place after being carried from another. the shape and direction of a river’s flow changes

6. Ch. 8 Plate Tectonics

7. Ch. 8.1 What are Earth’s layers made of?

8. Earth’s Variety Earth has a variety of surface features Mountains, valleys, plains, volcanoes, canyons, and flatlands, are a few Under the ocean, you can find trenches and ridges

9. Earth’s Layers Earth has many different layers Above the surface is the atmosphere The gases in the atmosphere allow us to live The outermost solid layer is the crust – Part we live on – Thickness varies – Part covered by ocean is 6-11 kilometers thick – Dry land is about 35-40km thick

10. Earth’s Layers Just below the crust is the mantle – Contains most of Earth’s mass – Outer part is solid rock – Inner part is so hot that the rock can flow slowly over time The innermost layer is the core – More compact than the mantle – Temperature is thought to be about 7,000 C which is as hot as the sun – Outer core is so hot it is a liquid – Inner core is solid

12. Earth’s Plates Earth’s crust and the upper part of the mantle are called the lithosphere The lithosphere is not a continuous layer It is broken into pieces called tectonic plates They are all different shapes and sizes The plates fit together like a puzzle Many of the plates are made of continental crust and oceanic crust Earth’s plates rest on a soft solid. They float on top of the lower part of the mantle

14. Ch. 8.2 How do Earth’s plates help create landforms?

15. Continental Drift In the early 1600s, scientists began to notice the coastlines of some continents looked like they could fit together In 1912 Alfred Wegener suggested that 225 million years ago the continents were all joined together in Pangea (all Earth) He introduced the theory of continental drift – Continents drifted apart in the past and continue to do so

16. Continental Drift The shape of the continents wasn’t the only evidence Plant and animal fossils found on the eastern coast of South America matched those found along the western coast of Africa Wegener felt this was impossible unless the species once lived side-by-side Matching rocks along both coasts also helped back up Wegener’s ideas But because they couldn’t find a force strong enough to move the continents, most people did not believe his idea

17. 100 million years agoEarth today

18. The Spreading Ocean Bottom There wasn’t much more evidence that supported Wegener’s theory Later, better methods to map the ocean floor were discovered Data was collected that showed long, deep ocean trenches and a chain of mountains along the floor of the Atlantic Ocean – Now called the Mid-Atlantic Ridge

19. The Spreading Ocean Bottom In 1960 an explanation for the trenches and ridges was made Was suggested that new crust forms at ocean ridges Magma, which is molten rock, pushes up through Earth’s crust When magma cools, it forms new crust More magma comes up and pushes newly formed crust and old crust aside Process is known as seafloor spreading

20. The Spreading Ocean Bottom Magma rises to fill gaps caused from plate movement Plate movement is caused from temperature differences When a liquid is heated, its particles move faster and spread apart Hot liquid weigh less and float above cooler liquids When it rises to the top, it cools, and more hot liquid can rise above This process is called convection The mantle is not a liquid, but its rocks are so hot they float slowly

21. Proof of Continental Drift Seafloor spreading helped support Wegener’s idea but it wasn’t enough proof In the early 1960s scientists were studying the magnetism of rocks near the Mid-Ocean Ridge In some places the magnetism faced north, in other places south Found alternating rows of north/south patterns spreading out from the Mid-Ocean Ridge Earth’s magnetism flips about every half million years’ When rocks form from cooling lava, the particular magnetic pattern is frozen into the rocks Evidence that alternating pattern of the rock has been slowly spreading out as new crust is formed

22. Ch. 8.3 How do scientists explain Earth’s features?

23. Theory of Plate Tectonics Scientists use the theory of plate tectonics to explain why Earth’s features appear as they do This theory states that Earth’s lithosphere is broken into about 20 moving plates Continents and ocean floor are the surfaces of the plates Plates are always moving in a continuous process in different directions

24. Theory of Plate Tectonics Scientists use GPS satellites in space to determine the distance between points on different plates They know from data that the North American plate and the Eurasian plate are moving about 2cm a year away from each other Mountains may form where plates move together, volcanoes when plates move apart

26. Plate Boundaries Plate boundaries are where two plates meet There are 3 types of boundaries – Spreading boundaries: plates move away from one another – Fracture boundaries: plates slide past each other. The break in the crust is called a fault. Earthquakes can occur here – Colliding boundaries: plates push against each other. When plates carry continents into each other, mountains can form. Other times volcanoes, ocean trenches or earthquakes.

27. Ch. 8.4 What causes earthquakes and volcanoes?

28. Earthquakes Plate movement takes place very slowly You can’t see it or feel it Jagged edges in the lithosphere sometimes stop movement Pressure builds up until it becomes to strong Rocks lurch forward and Earth’s crust shakes Earthquakes cause damage when pressure builds up along a fault line The underground point where an earthquake occurs is called the focus The point on Earth’s surface directly above the focus is called the epicenter Energy is carried out by waves. Waves spread out from the foucs and the epicenter

29. Earthquake Magnitude The strength of an earthquake is given as its magnitude The number shows the total number of energy released The Richter Scale is an example of a system used Each increase of 1 on the scale indicates about 31 times more energy released Magnitude doesn’t always indicate how much damage will be done

31. Volcanoes A volcano is an opening in the surface of one of Earth’s plates through which magma rises They mostly occur near plate boundaries Theory of plate tectonics explains why When a plate sinks beneath another at a plate boundary, the sinking crust melts into magma Pressure builds up from gases trapped in the magma If the crust of the overlying plate can no longer withstand the pressure, magma explodes through Magma that reaches the surface is called lava

33. Predicting Volcanoes and Earthquakes Predicting when volcanoes will erupt or earthquakes will occur is a challenge for scientists It is easier to predict when a volcano will erupt Scientists study maps of past eruptions Since volcanoes usually erupt in a pattern, this can help predict the next eruption Earthquake predictions are not as easy Scientists can find faults, but that isn’t always a direct indication They use seismographs to listen for tremors

34. Ch. 10 Reshaping Earth’s Surface

35. Earth’s Features There are many different types of landforms on Earth Water shapes a lot of these landforms Landforms can form from gradual or dramatic events

36. Weathering and Erosion Many changes to Earth’s surface can only be seen over thousands of years Most of these changes are caused by weathering and erosion There are 2 types of weathering, mechanical and chemical The rocks that break apart are eroded away Weathering and erosion are continuously changing Earth’s surface

37. Weathering and Erosion Weathering is the process of breaking down rock into smaller pieces These pieces are called sediments Mechanical Weathering: when forces such as water and ice break down rock. Minerals that make up rock do not change Chemical Weathering: Minerals that make up rock change When water, oxygen, or chemicals from plants change the make up of the rock Erosion: moves the sediments away

38. Soil Erosion Soil can be eroded very quickly Plant roots help keep soil intact But if nothing is planted, rain and wind can blow the soil away EX: the Dust Bowl in the 1930s Started an era of soil conservation

39. Ch. 10.2 How does water affect Earth’s features?

40. Deposition The high energy moving water has can break down rock and soil into sediments It can also chemically weather rock by dissolving minerals and other materials in the rock The sediments that form during weathering are eroded and deposited in another location This is called deposition In this process the shape and direction of a river’s flow change

41. Minerals in Lakes and Oceans As rivers flow to the ocean, they carry sediments and dissolved minerals Ocean plants and animals use some of these minerals Some settle out of water and from mineral deposits in lakes, along the coast, and on the ocean floor One mineral carried by water is salt Rivers carry an estimated 4 billion tons of dissolved salts to the oceans As a result of thousands of years of ocean water evaporating, the amount of salt has increased

42. River Systems While rivers and streams look like a flat, quiet body of water, they can change quite a bit over time A stream begins on land higher than sea level It flows because gravity pulls it downward to a lower area When many streams flow into each other, a river is formed Sediments carried by rivers are deposited in different places

43. Floodplains When rivers flood their banks, sediments are deposited Flooding can move huge amounts of sediments to places that normally wouldn’t receive them A floodplain is the area that is likely to receive the overflow from a flooded river Floods can be good for farmers, but can cause a lot of damage to houses

44. Ch. 10.3 How do waves affect coastal landforms?

45. Wave Energy When an ocean wave moves, only energy moves forward, the water stays in the same spot The water rises and falls in a circular motion As the wave moves closer to shore, the shallower ocean floor interferes with the waves movements The ocean floor causes the waves to slow down, while the top continues at the same speed

46. Causes of Waves Waves on open water are caused by wind The wind blows on the water and transfers energy The size of the wave depends on the speed of the wind They can also be formed through tectonic activity Earthquakes, volcano eruptions, and landslides under water can cause massive waves The events can form tsunamis, which are waves that travel at great speeds and reach great heights

47. Wave Characteristics Wave Length Crest Trough

48. http://www.educade.org/lesson_plans/create-your- own-flip-book-of-earths-surface-with-puzzling- plates-level-1 http://www.educade.org/lesson_plans/create-your- own-flip-book-of-earths-surface-with-puzzling- plates-level-1 http://www.britannica.com/science/plate- tectonics/Development-of-tectonic-theory http://www.britannica.com/science/plate- tectonics/Development-of-tectonic-theory https://www.studyblue.com/notes/note/n/geol- 130-study-guide-2012-13-horton/deck/9721521 https://www.studyblue.com/notes/note/n/geol- 130-study-guide-2012-13-horton/deck/9721521 http://www.thinkstations.com/homework- help/geography/volcanoes-violent-outbursts.html http://www.thinkstations.com/homework- help/geography/volcanoes-violent-outbursts.html